Mechanical stoker for forced draft furnaces



' 11, 1930. H, E w 1-z 1,781,487

MECHANICAL STOKER FOR FORCED DRAFT FURNACES Filed June 21, 1925 2 Sheets-Sheet l ATTORNEYS Nov. 11, 1930. H. E. WITZ MECHANICAL STOKE R FOR FORCED DRAFT FURNACES Filed June 21, 1925 2 Sheets-Sheet 2 INVENTOR Mam/K BY ATTORNEYS Patented Nov. 11, 1930 UNITED STATES Pa'rru'r OFFICE nnnar EMIL wrrz, or OBEBHAUSEN, GERMANY, Assrenon T0 mnn BABCOCK & wrncox conrnmr, onnevonnn, NEW JERSEY, A con-Pen TION or nEwJnnsEY MECHANICAL STOKER FOE Application filed June 21, 1923, Serial No.

This invention relates to improvements in 10 exposed partsof the furnace and stoker structure when operating with forced draft and to providemeans for withdrawing and leading away dust and furnacegases which would otherwise contaminatethe atmosphere of the boiler'room. The dust andfurnace gas, are, of course, liable to escape, due to the fact that in: a forced draft furnace the combustion chamber is under a slightly greater pressure than atmospheric.

The present invention, a while producing the same effect, permits of avoiding the closing in of the front of the grate, so that the grate is accessible from the front and the grate tract can be supervised.

Two embodiments of the invention are illustrated in the accompanying drawing, in which Fig. 1 is a vertical, longitudinal section of one embodiment. Fig. 2 is a similar View of a modification. Fig. 3 is a section showing some of the details of another modification.

Referring to Fig. 1 of the drawing, 1 is the combustion chamber, 2 the fuel hopper, 3 the upper run of the grate, which is shown somewhat diagrammatically in the drawings, a a sealing box arranged between the upper and lower runs, and 5a sealing plate arranged under the lower run, which, together with the box 4, completely seals the rear part of the grate from the front. 6 is a shutter or gate regulating the height of the fuel layer. Between the shutter 6 and the rear wall of the hopper 2 is provided a hollow space 7, which is connected by means of a duct 8 with the inlet side of a fan, with the chimney or with a boiler pass. The hollow space 7 is so constructed that the partial vacuum produced exerts its suction action both above the shut ter 6 and also at the side'thereof, so that, at this point, flue gases emerging from the furrcncnn nnar'r FURNACES 646,735, and in Germany August 3, 1922.

nace are,immediatelydrawn off and cannot therefore pass into the boiler house.

a The suction action is further increased by providinga sealing off plate 9 at the front end of thegrate beneath theupper run of the grate, permitting less air to pass from the boiler house into the hollow space 7.

Referring to Fig. 2, slots 11 are provided inthe boxi, these slots extending the width of the box. .The dust, which is forced forward through the grate interstices, owing to the forced draft pressure in the rear part of the grate, therefore passes through the openings 11 into the boxt and from there, through piping 12 connected tothe box, to a dust separator arranged in the basement, where it is separated out. Care need only be taken that the sealing surfaces in front of the opening 11, between which surfaces the grate passes, are selected of such length that the resistance opposed in this part to the passage of the air is greater than the resistance inside the box t, the piping 1-2 and the separator 13. The separator maybe of the usual cyclone construction, in which the airleaves the separatorthrough the pipe 120 while the .dustafter having been removed owing to the whirling action imparted to the air and dust mixture is withdrawnat 130. The separator is not absolutely necessary and the box may itself be constructed as a separator by meansof suitable baffles therein, as shown by the box 4" in Fig. 3. In this construction, fuel riddling throughfrom the upper run of the stoker may. be removed through the openingl lO of box 4", while the dust entering through the opening 11f fromthe lower run is removed through opening 110 and thus the fuel riddlingthrough the upper run of the stoker maybe recovered free from the dust from other parts of the furnace.

By means of an opening 14; or 14 provided in and passingthrough the upper side of the box or 4: respectively, the smoke-suction action on the lower run of the grate can also be increased. The openings 110 and 140, can, if necessary, be connected to the chimney or to another suction device.

1. In combination, a forced draft furnace having a chain grate stoker, means for supplying forced draft to the rear part of the stoker, a fuel gate to regulate the thickness of coal on said Stoker, a hopper spaced from said fuel gate and in front of the same, means for placing the region between the gateand hopper and abovesaid stoker under sub-at inospl eric pressure, a member fsealingnthe upper;- and lower runs of the stoker at the forward end thereof, and means for removng dust through said sealing means.

2., In combination, a forced draft furnace having a chain grate stoker, means for supplying forced draft to the rear part of the stoker, a member sealing the upper. and lower runs ofthe stoker at the forward end thereof, said member having'an aperture opposite a run of the stoker, and means for creating a draft 'from'said stoker through said aperture whereby dust is drawn-from the sto'ker into said member. I

3. In combination, a forced" draft furnace having a chain grate stoker, means for supplying forced; draft tothe rear part of the stoker, a'memb'er sealingtheupper and'lower runsof, the stoker at the forward end thereof, said member havingan aperture oppositea run of the stoker, means for creatst'oker, a sealing'device-for said stoker' com prising a box-like member located between the runsof the grate,said member-having sealing'surfaces for the upper andlbwer runs 1 of the grate at the forward end thereof, said memberbeing-provide'd Withfan aperture in asealing surface, a bathe-in said member in the path of gases passing through said aperture; and means for creating. a draft through saidaperture from said grate.

5. In a forced draft furnace,'a chain. grate stoker,'a sealing device for said stoker comprising abox-likemember locatedbetweenthe runs of the grate, said member havingsealing surfaces for the upper andlower runs ofthe grate, said memberbeing provided With an aperture in its upper and an aperture 111- its lower sealing surfaces, baffles in said member arranged so as to separate dust passing throughfrom the upper run independently ofthe dust from the lower run, and means for creating a draft through said aperture HENRIEMIL WITZ.

from said grate. 

